This invention relates generally to the field of telephony, and more particularly to telephone main distributing frames which are mounted in telephone offices for the purpose of supporting connector blocks on one side of the frame and protector blocks on the other side thereof.
In U.S. Pat. No. 4,313,039 granted June 26, 1982 to the same assignee as the present invention, there is disclosed a modular distribution frame having oppositely disposed sides, one of which supports connector blocks leading to inside plant equipment, and the other side of which supports protector blocks associated with outside plant cables carrying incoming subscriber pairs from a cable vault. To facilitate installation, corresponding protector blocks and connector blocks are pre-wired and include a cable stub, so that the box may be installed by first securing the protector block in position on one side of the frame, and passing the connector block and accompanying pre-wired cable through a horizontal opening in the frame to anchor it on the opposite side. The cable stub is then interconnected to the connectorized cable to complete the installation. Much individual wiring of connections at the installation site is thereby eliminated.
Where the protector block and connector block are approximately the same size, and may occupy corresponding areas on either side of the frame, the above procedure may be followed with little difficulty and the blocks are continuously accessible to service personnel both during initial installation and subsequent servicing operations. Often, the above-described frame must be used in conjunction with connector blocks which are appreciably larger than the associated protector blocks for reasons which are beyond the control of the manufacturer. A typical case is that in which the connector blocks are foreign design and cannot be substituted by blocks of more suitable size without affecting the compatability of the other components of the system. Thus, such connector blocks must be a part of the installation, notwithstanding the fact that they are less efficient from the aspect of subscriber pair density, and are awkwardly configured. Such blocks are not conveniently arranged on one side of the frame without wasting a substantial amount of the area available for mounting. On the other side of the frame, there is still present the need for accessibility of protector modules to service personnel, notwithstanding that access of the connector blocks is not normally required after installation.